The invention relates to means and methods for preventing and protecting automobile windshields from damage caused by impacts from flying objects. In particular the invention relates to a barrier placed around the periphery of the windshield to absorb the impact from objects and thereby prevent damage.
Damage to windshields caused by debris or other impacts has long been a problem. Many patents have issued and a substantial business thrives respecting the repair of such damage. For a long time it was believed that long cracks, that is cracks over six inches in length could not be repaired. However, shorter cracks referred to as stone damage were repairable. Later through significant developments in the field it became possible to repair long cracks. Patents which relate to the repair of long cracks in windshields are U.S. Pat. Nos. 5,116,441, 5,425,827, 5,429,692, U.S. patent application Ser. Nos. 08/436,155, 08/436,591 and 08/459,039.
Also, there is a thriving business in the replacement of cracked windshields which either cannot be repaired or which are believed to be unrepairable. In fact replacement is vastly more common than repair.
Despite these thriving businesses damage to windshields present costs to the consumer because of the cost of the repair or replacement. When insurance covers the damage then there is an insurance company loss which is passed on to consumers through their premiums. Also tons of unrecycled waste are created year after year.
Impacts which cause damage near the glass edge nearly always result in an edge crack, that is a crack running through the impact point to the edge of the glass. These cracks are also nearly always long cracks, that is over 6 inches in length. By contrast impacts in the middle area of the windshield quite often result only in the limited damage known as chips or stone damage, that is a bullseye, a star break or a combination and absent any long crack. Thus the problem of windshield damage in the peripheral area is considerably greater than in the middle. Long cracks, especially edge cracks, demand attention soon after cracking and most end up being replaced.
Windshields are installed with a rubber or plastic and in some cases metal, molding. Presently, most moldings are 1-2 centimeters wide, about 50% of the molding width extending over the glass. The maximum known molding width covers 2 cm of the windshield glass.
In the past a windshield was prepared with a pre-installed molding prior to shipping called xe2x80x9cencapsulated.xe2x80x9d This molding was a conventional molding covering about 1 centimeter of glass and was not intended to prevent damage from impacts. They are hard to remove and install and are being discontinued.
The present invention provides a means and method for protecting a windshield from damage and therefore the development of cracks due to stone or other impact on windshields around the peripheral area. According to the invention, an impact resistant barrier is placed around the periphery of the windshield. The barrier is preferably a clear polymeric film, but could be opaque rubber, plastic or metal. The barrier is placed on the glass surface and in contact adjacent to the windshield molding. The width of the barrier is selected to eliminate the higher incidence of damage in the peripheral area; but the width may differ between sides, top and bottom, and it may differ in various vehicles. In one form of the invention, a clear plastic film is adhered to the windshield around its periphery to a selected width from the windshield molding. The clear plastic film will absorb impact from flying debris and allow visibility. As an alternative, equivalent protection can be obtained by a wider molding. Also, the film need not be clear in all portions of the windshield. The barrier can be installed before the windshield is fitted to the vehicle in which case it could extend to the edge of the glass.
In an alternate preferred embodiment, a clear polymeric film is from 6-10 mils thick and a preferred thickness is 6-8 mils, most preferably 7 or 8 mils. The range of 6-8 mils and the 7 mils thickness being especially preferred or bowed windshield portions as thicker films are too stiff.
In another alternate preferred embodiment, the clear film is a polyester. A further preferred embodiment is a clear laminated multi-layer, preferably 2 layer polyester film 6-10 mils thick, more preferably 6-8 mils thick and most preferably 7 or 8 mils. The range of 6-8 mils and the 7 or 8 thickness being especially preferred on bowed windshield portions.
In another preferred embodiment, the impact barrier is applied as a fluid which forms a film. The fluid may be applied by any desired method such as by spraying, dipping, or rolling.
In another preferred embodiment, the film may be not only on the front surface of the windshield, but also on the edge portion and on the back surface.
In another preferred embodiment, the impact barrier may be combined with a portion which serves as a molding. It may also be constructed of material which is ultra-violet absorbent to protect urethane which is used to install the windshield.
The impact barrier preferably has a width on the front of the windshield from the edge of from about 1 to about 3 inches, more preferably of from about 2 to 3 inches, and most preferably of about 3 inches. The width at the bottom may vary depending on the vehicle""s construction.
The impact barrier embodiments of this invention are known to provide prevention of a high percentage of cracks in windshields on passenger vehicles.
The impact barrier could also be applied to tempered glass such as the backglass and quarterpanels. These are made of tempered glass, but the backglass may only be a single layer and quarterpanels are single layers. These are more susceptible to shattering when hit near the edge. Therefore, use of the present invention on the tempered glass outside surface prevents such breakage.
The windshield has an important interaction with the passenger side air bag, since upon deploying it pushes against the windshield. Consequently, the windshield must stay in place in order that the passenger side air bag functions properly. It has been found that replacement windshields which have not been properly installed can pop out when the air bag deploys against it. The present invention prevents the damage which eases the need for replacements.